It is known that poly-p-phenyleneterephthalamide (to be sometimes referred to as “PPTA” hereinafter) typified by Twaron and Kevlar and poly-p-phenylenebenzobisoxazole (to be sometimes referred to as “PBO” hereinafter) typified by Zylon are useful as raw materials for fibers and other formed products excellent in heat resistance and mechanical properties.
Patent Document 1 describes benzobisoxazole and a process for the production of a pyridine-benzobisoxazole copolymer.
Patent Document 2 describes a production of a film or fiber, in which an aqueous solution of an alkali metal salt of an aromatic polyamide having a biphenylhydroxy group as a substituent is extruded into a coagulating liquid, followed by forming and stretching or drawing.
(Patent Document 1) WO85/04178
(Patent Document 2) GB1142071